A technique related to a motor has been proposed. For example, a brushless motor is disclosed in Japanese Unexamined Patent Application Publication No. H05-219708. This brushless motor includes a housing having a tubular portion. A bearing is attached to an inner surface of the housing. A thrust plate is held at a corresponding position of a shaft. A rotor yoke having a rotor magnet is secured to the shaft. A steel ball is secured to an end surface of the shaft.
An electric motor that is driven by an inverter device is disclosed in Patent Literature 2. In this electric motor, a first sliding element is attached to a shaft end portion of a conductive rotating shaft of a rotator. The rotating shaft is borne in a rotatable state by a rolling bearing. The rolling bearing is held at an outer ring by a conductive bracket. A conductive cover is attached to the bracket. A second sliding element is attached to the cover. The second sliding element comes into contact with the sliding element by a biasing force of a conductive elastic body. The elastic body is a flat spring or the like. According to this electric motor, when the electric motor is driven by the inverter device, the two sliding elements are continuously brought into sliding contact with each other, and accordingly, electric charge generated on the rotating shaft can be released to a fixed portion such as the bracket not via the rolling bearing. It is possible to prevent electrolytic corrosion of the rolling bearing and promote the enhancement of longevity of the electric motor. In addition, a rolling bearing including seal plates is disclosed in Japanese Unexamined Patent Application Publication No. H09-291943. The seal plates are made of a conductive flexible material, and are in contact with an inner ring and an outer ring.
An electric motor that can reduce electrolytic corrosion of a bearing is disclosed in Japanese Unexamined Patent Application Publication No. 2008-263698. This electric motor is driven by pulse-width modulation control. The electric motor includes a case, a stator core, a wire, a rotator core, a bearing, and an insulator. The case is grounded. The stator core is attached to the case. The wire is wound around the stator core. The rotator core is provided with a metal rotating shaft. The bearing has an outer ring and an inner ring. The outer ring is attached to the case. The inner ring supports the rotating shaft. The insulator is disposed, in contact with the bearing, on a path from the rotating shaft to the case via the baring. The insulator is set to 1 mm or more thick.